Many off-road enthusiasts remain concerned about the functioning of the rev limiter. Rev limiter is very crucial to protect the engine in case of over speed. But the major question that arises so often is about the rev limiter: Is it dangerous to hit the rev limiter when off-roading?
Hitting the rev limiter can slow down your off-road journey and waste your fuel. In case your engine is revved high on a long-term basis, it can impart wear and damage to a larger extent. It is better to prevent hitting the rev limiter in neutral as rapidly revving an engine can heat the piston.
A rev limiter can be defined as a device comprised of an internal combustion engine and connected to modern vehicles. The main function of the rev limiter is to prevent the damage imparted to the engine in case of overspeeding.
Usage of Rev Limiter:
Rev limiters are used to limit the speed limit of the vehicle to protect the engine. By using a rev limiter, the vehicles can’t attain the maximum speed limit during driving.
Every engine of the vehicle is designed so that it cannot endure over-speed issues as it is designed to function up to a certain speed. Rev limiters are used to restrict the maximum rotational speed of any car, which is measured in revolutions per minute (RPM). Limiter comes into action to prevent the vehicle engine from surpassing the red line. Engine damage to the vehicle is probably beyond the red line.
What Happens Beyond the Red-Line?
The Redline of any engine can be adjusted between 100 to 12,000 RPM. There is no fixed limit to be adjusted; different manufacturers set the limit differently.
Damage to the valvetrain and piston occurs when the engine of the vehicle crosses the adjusted speed limit.
Due to over-revving valve remains open longer than usual. Damages that can take place due to this opening are associated with a misfire, loss of compression, and colliding of valve and piston with each other.
In some cases, the engine cannot withstand the impacts and needs to be replaced permanently. You should better understand the red line that refers to the maximum engine speed at which internal combustion engines can be operated without any damage to any of these components. Still, damage can be occurred due to a violation of this speed limit.
The Redline of an engine is dependent on many components, including balance of components, displacement, and mass of components. Most modern vehicles hold computer systems that function to prevent the engine from over speed by cutting out the fuel supply or breaking down the ignition system.
This device is known as the rev limiter that is crucial in the functioning of the vehicle engine and prevents it from being damaged.
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Difference Rev Limiter and Red-Line:
The maximum speed in rpm that your engine can run safely without causing damage to itself is typically denoted by a red line or red section on your tachometer.
The Redline is just a graphical representation of the rpm beyond which you shouldn’t exceed your Rev limiter. The Redline is usually set significantly below the rpm of which your engine can withstand; the red line varies with many factors, including component weight stroke and the displacement of your engine.
You should have an idea that diesel engines typically have a much lower red line than gasoline engines.
Now there is a difference between the red line and your rev limiter. You are limiting your engine’s rpm so that you don’t cause any damage to it. Your car’s ECU will cut fuel until the engine drops below the red line.
It can also be done by ignition control via the spark plugs, but that’s a lot less common.
Suppose you’re driving an automatic car, then your vehicle won’t even let you pass the red line. Most automatic vehicles have tendency to upshift automatically as you approach the red line or rev limiter.
However, if you are in a DCT equipped car in manual mode or you’re driving a standard manual transmission, you can bang off the rev limiter as much as you want.
Impact of Over-Revving:
Over revving can prove to be very bad for the performance of your engine. But you can avoid the damage due to over-revving because you can instantly know about the damage caused by over-revving. These are the most common impacts imposed by over-revving as follows:
|Damages Due to Over-Revving||Consequences|
|Damage to the valve train||Valvetrain can be damaged by over-revving as it caused the valve train to be open for a long period of time. Valve stuck between the open and close state and this state leads to the valve float. This problem of valve train can lead to loss of power to the engine and sometimes also cause engine misfire.|
|Damage to clutch or flywheel||The wheels of your vehicle are connected to the engine by a clutch system. The engine of your vehicle imparts power to the wheels to start your journey. Over revving can cause serious damage to the clutch system off your vehicle.|
|Damage to connecting rod||The piston of your vehicle is connected to the crankshaft through these connecting rods. The location of the connecting rods is very sensitive as they are located near the internal combustion engine. Any damage to these connecting rods can lead to catastrophic engine failure.|
Steps to Avoid Over-Revving:
Over revving can cause serious damages to the functioning of the engine of your vehicle. But you can protect the damages imposed by over-revving by following steps:
Pushing the Clutch System:
Pushing the clutch can disconnect the power supply between the engine and wheels of your vehicle. This will prevent the engine of your vehicle from getting over-stressed due to extra weight. This needs to be done quickly to avoid engine failure.
Replace the Shift Knob or Rev Limiter:
You can also tackle this situation by replacing the old shift knob with the new one or replacing the rev limiter.
The engine is the main component of your vehicle that determines the vehicle’s functioning; you should maintain the engine’s performance by taking these necessary steps.
How Does the Rev Limiter Prevent Damage?
You should have an idea about the red line that is the start of the engine speed zone; it is better to surpass that zone as quickly as possible as it is not good to stay within that limit for a long time. Rev limiter comes into action to prevent the engine speed.
As discussed earlier, the valve remains open due to over speed and cause much damage to the engine. Limiters mainly set aside those components that can cause combustion. Combustion can lead to big damages; it needs to be prevented at the right time. Otherwise, it can impart harmful damages to the vehicle.
The limiter is the key player to do this task by shutting off these types of dangerous components. But compression-ignition engines can get damage due to electronic-fuel injectors by using mechanical limiters.
On the other hand, a spark-ignition engine can prevent damage by shutting off the fuel. They can also reduce the engine power by changing the engine timing. Rev limiters are not largely required in automatic transmission because the engine revolution per minute stays within the control limit. Rev limiters are only required while going through the manual mode.
The tachometer is absent in these vehicles, but there is no risk of speeding, so engine RPM is not a concern. Rev limiter in this way prevents the risk of damages associated with the speed of the engine.
Over Speed and Its Prevention:
Over speed can be termed as the situation where the engine can surpass the design limit, and this situation is very critical for the normal functioning of the engine.
The extent of damage imposed by over speed depends upon the type of engine; some types of the engine can endure this abuse more efficiently than the other one.
The most important factor which determines the extent of damage is the duration of the speed limit. Few engines are not capable of enduring even minor abuses. Revolution per minute can be regarded as the setpoint to measure the engine’s speed.
The major device that can prevent the damages imposed by over speed is the rev limiter.
What Allows an Engine to Rev Higher and Its Benefits?
The major factor that can allow the engine to rev higher is associated with piston speed. Lower piston speed is the main factor that will allow the engine to rev higher.
Stress on the connecting rods can be reduced by lowering the speed of the piston that will help the engine to rev higher.
Another factor that allows the engine to rev higher is the size of the bore. The wider bore allows the engine to rev higher. The biggest benefit associated with higher rev is the provision of high power to the engine.
Horsepower is associated with the rpm and relevant torque. If you want to increase the horsepower, you can achieve this by maximizing the torque and rpm of the engine.
You can also increase the power by increasing the displacement, but it can reduce the engine’s efficiency.
Types of Rev Limiters:
|Soft-Cut Rev Limiter||Hard-Cut Rev Limiter|
|Soft cut rev limiters are particularly used to cut off the supply of fuel to the engine. The main advantage of these engines is that they have the capacity to stationed the ignition timing. |
Another main function of soft cut rev limiter is associated with the use of the engine as with the connection to soft-cut limiters, the engine of the vehicle can cut the fuel or stationed the ignition timing before the set RPM.
Soft cut limiters can prevent damage but they are not as efficient as hard-cut rev limiters. Soft-cut rev limiters can function properly but their performance is not going to surpass hard-cut rev limiters.
|Hard-cut rev limiters are more efficient in their functioning as compared to the soft-cut rev limiters but they are used to completely cut down the fuel or spark to the engine. |
You have to know about the functioning of these types of limiters as they get activated at the set revolution per minute and they can be recreated in case of application of throttle.
Spark Control Rev Limiters:
Spark control rev limiters are connected with the vehicle to control the spark. Spark control rev limiters function by switching off the spark plugs. Spark plugs can cause overheating, and internal damage to the engine, but spark control rev limiters prevent this from happening.
Spark control rev limiters come into action in case of overspeeding. Once the engine over speeds, there are more chances of ignition. Production vehicles are not susceptible to this damage because the system can inject fuel into the cylinder.
Spark control rev limiter is the most efficient type of rev limiter to avoid the ignition at any level that can prove deadly dangerous for your vehicle.
Fuel Control Rev Limiters:
Fuel control rev limiters are used to cut the fuel, and they are the most common type of rev limiters. These types of rev limiters are specialized as they wear less on exhaust components that signify their efficiency.
Fuel control rev limiters are most efficient in their functioning.
These rev limiters are used to lean out over the engine’s speed by shutting down the fuel injectors.
They perform this function efficiently as there are fewer chances of combustion. But this engine type has the sole drawback as their performance gets hurt due to high temperature in lean operations.
What happens by removing the Rev Limiter?
Rev limiter is a device that is also called a revolution per minute, and it is connected to many vehicles. This device is mainly attached to modern vehicles.
There are many advantages of this device as it indicates the point when engine speed exceeded normal point. Rev limiter is required for the good performance of the engine.
When the revolution per minute becomes too high at that moment, the rev limiter functioned to prevent overloading by sending the electric current to the coil. This is the most important function of the rev limiter. Sometimes it becomes necessary to remove the rev limiter. You can avoid many technical problems by removing the rev limiter.
It is advisable to remove the rev limiter physically to avoid any damage. You have to be very careful in doing this task. Otherwise, your vehicle can get badly damaged. You can hire the service of an automotive expert to get this job done.
Frequently Asked Questions (FAQs):
How does the engine breath at high rpm?
The valvetrain is a decisive factor in determining the engine breath at high rpm. If the vehicle possesses a larger bore, it will allow for larger valves. Thus it imparts more airflow at higher rpm.
It can be said that the larger valve can lead to valve float. But it is more challenging for engines to have two valves per cylinder. But you can overcome the problem associated with valve float by using the stiff valve spring.
But you should bear in mind that more energy is required, and the system is not much efficient in doing so. You can use valves made up of lighter material to prevent the use of stiffer valves.
In this way, you can tackle this situation proficiently. It would help if you took care of these sensitive issues associated with valves.
Can Redline damage your engine?
Redline is not the cause of engine damage; it will not do any harm to the engine. You can treat it as badly as you can, but it will not cause any damage to your engine. This is why engine revving is not a problem; you can do this several times in a weak without causing any damage.
But if your car is undergoing red lining consistently, you can face problems associated with tires. Tires are the essential components of the vehicle, and you can not afford this.
You can undergo to redline your car once in a while only if you drive your car carefully. Redline is very effective in blowing any excess of carbon out of the combustion chambers, and this practice is very effective in cleaning the valves. You can do this if you are desired to do this activity; it will not cause any harm.
What happens if you rev your engine too much?
Over revving can prove to be deadly for many vehicle components, but the most impacted components of the vehicle are piston and valve terrain. The extent of damage to these components can be augmented many times if the valve is kept open.
Many issues can be erupted due to valve float, and the most obvious issue associated with this is loss of compression that can prove costly for your vehicle. Many other issues are associated with this, which are misfire or the collision of valve and piston together.
Most people are also concerned about this issue that whether revving is legal or illegal. Revving is not an illegal activity; it is a legal issue.
Can high rev per minute damage the engine?
High rev per minute causes absolute stress on the engine of your vehicle. This is the point where the engine has to endure the most pressure. The extent of endurance depends upon the type of engine.
Those forces directly applying to the rotating assembly can be increased exponentially with the increase in rev per minute.
Another main issue associated with the high rev per minute is the magnification of oiling inconsistencies, and this can prove to be deadly dangerous for the engine’s efficiency.
What do 2 step rev limiters do?
The main feature of the two-step rev limiter is that this device is comprised of two separate RPMs, and the rev limiter is set according to the conditions.
Both limiters are set differently, and you should have an idea about the connection between these limiters. The first one is set when the car is stationary, and it ensures the protection of the engine. The second rev limiter is the Redline that prevents engine damage.
The engine of the vehicle is the essential component which governs the performance of the vehicle.
This is Surya. I am an experienced off-roader. I have been off-roading for many years across several terrains. I am passionate about 4×4 driving and want to share my knowledge and experience with others.
My goal is to provide you with the most comprehensive and unbiased information about off-roading.
I curated this article through my personal experience and expertise, and I hope it helps you with what you are looking for.